1. Field of the Invention
The present invention relates to devices that deliver uniform quantities of light energy to treatment surfaces.
2. Information Disclosure Statement
Light energy is used in a multitude and variety of industrial and medical applications. For example, light energy may be employed for many cosmetic skin treatments including: 1) the removal of vascular lesions, benign pigmented lesions, and tattoos, 2) the abatement of blemishes within the lower dermis, 3) the removal of unwanted hair, 4) the creation of skin pockets during hair transplantation surgery, and 5) the shrinkage of varicose veins. These applications typically require light sources such as a pulsed dye, carbon dioxide, erbium, ruby, argon, alexandrite, copper vapor or Nd:YAG lasers. Additionally, diode light sources such as laser diodes, frequency-doubled laser diodes, tapered laser diodes, diode pumped solid state lasers, frequency-doubled diode pumped solid state lasers, diode pumped fiber lasers, or super luminescent diodes may be employed.
Most currently performed light energy (photonic) dermatology treatments involve either selective photothermolysis of pigmented structures within skin or involve char-free vaporization of skin. Selective photothermolysis is the precisely controlled destruction of unwanted pigmented structures in the skin. This process avoids significant harm to overlying or surrounding tissue that might result in scarring. Pigmented structures targeted by this method typically include melanin particles, enlarged blood vessels and tattoo ink particles. An operator selectively heats targeted structures until they are photo-coagulated or photo-disrupted, and the skin""s natural physiological mechanisms break down and remove the light-altered remnants.
Selective photothermolysis removes tattoos by targeting the embedded ink particles. A wavelength that is well absorbed by the ink particle breaks up the particle, and the remnants then slough off. The procedure may require multiple wavelengths, depending on the number and kinds of inks used in the tattoo.
Hair removal is one of the largest potential markets for aesthetic photonic equipment and treatments. Hair removal methods rely on selective photothermolysis interactions with hair follicles. Although the underlying mechanisms are not completely understood, they most likely depend upon the type of light source and specific method employed. In one method, a carbon-based ointment is rubbed into the hair follicles. The carbon particles serve as the primary absorbers of light energy. In other xe2x80x9cointment freexe2x80x9d methods, melanin particles lining the hair follicles are thought to absorb the light energy. The broad absorption curve of melaninxe2x80x94the natural skin pigment responsible for skin""s brown colorxe2x80x94allows selective heating of subsurface melanin particles by numerous visible and near-infrared wavelengths. Depending on the patient""s skin color (melanin content), however, some wavelengths may be more effective because they better penetrate overlying skin.
Another important example of a target tissue present throughout the body is the vasculature that contains erythrocytes. The erythrocytes contain hemoglobin, a naturally occurring chromophore with a broad usable absorption band in the visible region. The entire range of visible wavelengths shorter than approximately 600 nm and extending into the ultraviolet is available to purposely inflict damage to target tissues containing this chromophore. The specific wavelength selected depends on 1) the relative effects of scattering, which varies with wavelength, 2) the presence of other chromophores, such as melanin, in the adjacent or overlying tissues, and 3) the availability of light sources.
The second major method of photonic dermatology treatment is char-free vaporization. In this method, certain types of light sources are employed to vaporize soft tissue with little or no carbonization, while also controlling bleeding. These qualities afford practitioners a high level of surgical precision and control. Removal of upper skin layers in areas with wrinkles, acne scars or other blemishes usually results in xe2x80x9cde-emphasizedxe2x80x9d wrinkles or blemishes after healing. During the healing process, the patient can use makeup to hide reddened skin (erythema), which can last for weeks or months after the treatment. xe2x80x9cNon-ablativexe2x80x9d methods represent a fundamentally new way to resurface the skin. Instead of vaporizing upper skin layers, light energy selectively heats collagen fibrils in subsurface layers, which stimulates the skin to make new collagen and xe2x80x9cremodelxe2x80x9d itself, de-emphasizing wrinkles. Selective heating of appropriate layers, several hundred microns below the surface may require simultaneous deposition of a coolant to the tissue surface to prevent damage to the epidermis (Manni, Jeffrey G., Biophotonics International. Vol. 5 (3), 1998, 40-7).
A method of applying coolant liquid to the skin surface to prevent tissue damage was also described in U.S. Pat. No. 5,454,807, entitled xe2x80x9cMedical Treatment of Deeply Seated Tissue Using Optical Radiationxe2x80x9d, invented by Charles D. Lennox and Stephen P. Beaudet. The ""807 patent is hereby expressly incorporated by reference as part of the present disclosure.
Simultaneous application of light energy and coolant in dermatological applications allows greater amounts of energy to be transferred to the dermis without injuring the overlying skin layers. Coolant applied at the treatment surface limits the elevated temperature range to the micro-vessels in the dermis to avoid any tissue damage and scar formation as a result of a dermatological procedure. The tissue surface can be cooled with a stream of fluid such as water, saline, and gaseous nitrogen, oxygen, or carbon dioxide.
In addition to simultaneous application of light energy and fluid material, it often is advantageous to uniformly distribute light energy to a larger surface area, e.g. a surface area of 10 mm2 or larger. Uneven distribution of light energy may lead to too much or too little energy at certain portions of the work or treatment site. This can require re-treatment that is costly, and subjects the patient or the work piece to an increased risk of scarring (damage) or other problems that may occur during the procedure. For example, epidermis receiving too much light energy may become charred and change colors, leading to absorption of light energy destined for the dermis. Contrarily, if not enough light energy is applied to a site, the desired tissue change may not be attained. These negative effects are often realized in manual treatments because it is difficult to manually distribute energy uniformly. Thus, the skill of the practitioner in manual treatments has previously been of utmost importance for manually administered techniques.
In order to overcome the problems of non-uniformity of radiation, various scanning photonic delivery systems, typically incorporating a computerized sub-system, have been suggested. For example, Ortiz et al. (U.S. Pat. No. 5,474,549) teach a system that provides for a uniform fluence level throughout a treatment site by scanning the light beam at a predetermined, controlled velocity (i.e. a controlled speed and direction), and predetermined pattern. However, the problem with this and other similar state of the art systems is that it is difficult to treat irregularly shaped areas that may be treatable by a manually operated photonic delivery system. State of the art computerized systems have a limited number of scan patterns, for example square, line, rectangle, rhombus, serpentine, triangle, or hexagon. Manually controlled scanners, however, can be manipulated to an unlimited number of scan patterns. An ideal laser scanning and delivery device, therefore, would offer the measured distribution of radiation of a computerized system and the scanning flexibility of manually controlled systems.
Additionally, computerized scanning systems can be very complicated, requiring intricate and expensive machinery. These systems may work well for a small two-dimensional treatment site, but may fail to treat larger three-dimensional formed areas or surfaces that are more commonly encountered in work and treatment applications. These three-dimensional treatment areas are commonly treated manuallyxe2x80x94a procedure inherently dependent on the skill of the operator.
U.S. Pat. No. 4,733,660 describes a light energy delivery hand-piece that provides an adjustable scanning mechanism that manipulates the dwell time of a focused light energy spot, thereby controlling the light energy absorbed by a target material. Specifically, the dwell time of the light energy beam is designed to match the thermal diffusion time for destruction of the wall of an abnormal vessel, and some surrounding collagen.
The Itzkan system of ""660 fails to provide for a uniform distribution of energy throughout a work or treatment site. Moreover, it is difficult to determine the thermal diffusion time for destruction of the wall of an abnormal vessel because it depends on relative effects of light energy scattering, which varies in the presence of chromophores, such as melanin or erythrocytes in adjacent or overlying tissues. In exactly the conditions experienced in general application, the greatest problem with the Itzkan system is present.
It is therefore the aim of the present invention to provide a manually operated photonic scanning and delivery device that can deliver controlled amounts of energy to sites, especially irregularly shaped treatment or work sites.
It is therefore an object of the present invention to provide a manually operated photonic delivery system that can controllably deliver light energy to a treatment or work site.
It is another object of the present invention to provide a manually operated photonic delivery system that can uniformly deliver light energy to a treatment or work site.
It is yet another object of the present invention to provide a photonic delivery system that may be manually maneuvered in unlimited patterns to be especially applicable for irregularly shaped work or treatment sites.
It is an aim of the present invention is to provide a photonic system that may be operated in contact or non-contact mode.
Briefly stated, the present invention provides a photonic scanning and delivery system capable of controlled transmission of light energy to an irregularly shaped treatment area. The desired uniformity (controllability) of light energy application is ensured by a tracking device, which monitors the position of the radiation applicator and thereby prevents over-/under-radiation. The system employs a light energy delivery hand-piece. By these means, structures in the lower dermis are irradiated. The hand-piece can operate while in contact with a treatment surface. A treatment surface includes non-medical work sites. Alternatively, the hand-piece can operate in a non-contact mode. The system can also be used in non-medical applications such as UV or laser curing.
The above, and other objects, features and advantages of the present invention will become apparent from the following detailed description read in conjunction with the accompanying drawings. Items illustrated in different figures that have equivalent numbers are substantially identical.